The Commission for Protection of Competition said Telenor Bulgaria had told consumers over a period of 10 months from November 2015 that they could upload and download mobile data faster than the company's 4G LTE network was capable of.

The Commission said in a statement the company's website said consumers could download and upload content at speeds which did not match the achievable maximum speed of the processing network.

Telenor Bulgaria, which has 3.5 million subscribers in the Balkan country, said it was disappointed with the ruling and disagreed with the findings and the imposed sanction.

"We are currently reviewing in detail the decision of the Commission and will comment further when this review is completed," Telenor Bulgaria said in a statement.